1. Field of the Invention
The present invention relates to high-current, electrical quick-disconnect terminals and bus bars for distributing power from and to printed circuit boards, and more particularly, to such terminals and bus bars for electronic power supplies.
2. Description of Related Art
Bus bars are used for distributing electrical power from and to the power planes and ground planes of printed circuit boards. Such bus bars are fastened or soldered to an exposed portion of the ground plane or power plane of the circuit board, sometimes using plated through holes. Typically, bus bars include plated through holes for attaching ring terminals, or similar terminals, using threaded fasteners.
Power supplies are often used to supply power to numerous other components which together comprise a system, such as a computer network system. Thus, numerous power and ground wires connected to numerous other components may be connected to a single power supply. Additionally, wires connected to power supplies are disturbed relatively frequently, as components of the connected system are changed during system reconfigurations or for servicing.
Prior art power supplies do not provide an interconnect that is capable of handling multiple styles of connectors using a single, compact part mounted on the power supply. Users of power supplies currently use a wide variety of connectors and terminal devices to connect to power supplies. Power supplies must be manufactured to accommodate a variety of such connectors. At the same time, however, it is desirable to build a standard version of a power supply that does not require assembly of different interconnect components for different users, to reduce inventory and assembly costs.
Connections to prior art power supplies are also limited by heating caused by electrical contact resistance. Connections to power supplies in general operate at relatively high current levels, making them especially prone to heating from electrical resistance. This is particularly true in view of a trend towards lower voltage requirements, e.g., 3.3 volts and lower, for many modern electronic components. At these relatively low voltage levels, electrical currents are correspondingly higher when providing the same total power levels. Voltage drops in power supply interconnections will double and triple when current levels double and triple if not accompanied by a corresponding reduction in the electrical resistance of the interconnection system. In addition, voltage drops considered acceptable in a 12 or even 5 volt system become unacceptable in an even lower voltage system since they become a very high percentage of the delivered voltage. For example, a 50 amp power supply with an electrical interconnect having a 10 milliohm connective resistance results in a 0.5 volt drop at the interconnection. In a 1.8 voltage power supply this would be unacceptable. Consequently, reducing the electrical resistance of the connection to the power supply has become more important.
Heating from electrical resistance also imposes design constraints on prior art interconnects for power supplies, limiting the current capacity of each interconnect and increasing the number of connections that must be made to a single power supply just to carry the primary voltage. This in turn has hindered design of more compact power supplies by requiring more volume and panel space to accommodate the additional interconnections.
Prior art power supplies typically utilize a bus bar to distribute power from one location to another on a printed circuit board within an electronic system such as a power supply. Connections for power distribution to external electronic devices are typically made using flag terminals, other types of terminal devices, or other commercially available electrical connectors, with one side attached directly to the printed circuit board (PCB) usually by soldering. Cabling leading to external devices is typically connected to the mating halves of the above mentioned connectors. For example, quick-disconnect receptacles or ring lugs are crimped or otherwise attached to the wire cabling. Thus, in a typical prior art power supply, the interconnect resistance between the bus bar and the external cable wiring includes resistance from the bus bar-PCB connection resistance, the PCB trace resistance, and the PCB to terminal resistance, in addition to the connective resistance between the wire, the wire connector, and the terminal. A further disadvantage of prior art power supplies is that the terminal connectors require more space on the panel of the power supply than is necessary to efficiently accommodate external connections.
In some configurations, an external wire is connected directly to a bus bar using a threaded fastener. While reducing output power interconnection resistance, this configuration does not provide for use of commonly used quick-disconnect connectors to connect to the power supply. Quick-disconnect connectors are friction-fit devices that provide a convenient, removable electrical connection without the use of threaded fasteners or solder, and are considered a practical necessity by many users.
Therefore, objects of the present invention are to provide an integrated high-current interconnect and bus bar that provides for less electrical resistance, higher current capacity, cooler operation, interconnect capability for quick-disconnect connectors, and more compact design than afforded by prior art interconnects and bus bars. Further objects of the invention are to provide a bus bar that eliminates the need for separate interconnect terminals, to provide for multiple interconnection capability for multiple styles of connectors with a single component, and to provide for connection of multiple terminals.
The present invention provides a bus bar with integrated quick-disconnect terminals for distributing electrical current from a power supply or other electronic component. The bus bar and terminals are comprised of a single piece of copper alloy or other suitable electrically and thermally conductive material. The quick-disconnect terminals are blades configured to connect to industry standard receptacles. The bus bar additionally includes integral threaded inserts, threaded studs, or plain holes to provide direct attachment of lugs or other terminals using threaded fasteners, and pins or feet for electrical engagement with power and ground traces on a printed circuit board.
Advantages of the present invention include reduced panel space and volume requirements for the interconnect portion of a power supply or other electronic component incorporating the present invention. The present invention provides for higher electrical performance of the bus bar/interconnect system. Because the connection between the connector and the bus bar is eliminated, resistance is lowered and current capacity is increased. Additionally, the integrated construction provides for improved conduction of heat away from the connector, thereby reducing its operating temperature and allowing a higher current rating for the interconnect. Additional advantages include cost savings by eliminating the need for separate terminal parts, and providing for connection using a variety of different methods without requiring installation of different connectors for each type of application.
A more complete understanding of the high current interconnect and integrated bus bar will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings which will first be described briefly.